1. Field of the invention
The present invention disclosed broadly relates to a shaft tube on which a functional member is to be mounted and a hollow shaft member which comprises the shaft tube and the functional member, and manufacturing methods of the shaft tube and the shaft member. More particularly, the present invention relates to a shaft tube and a hollow shaft member suitable for a paper feed roller or the like mainly used for business machines such as a copying machine, word processor, facsimile etc., and also relates to manufacturing methods of the shaft tube and the hollow shaft member for that purpose.
2. Description of the Prior Art
Many shaft members are used for a paper feeder, copyholder, platen etc. in business machines such as a copying machine, word processor, facsimile etc. The shaft members are usually of solid steel. The solid material is heavy and expensive. The inventor of the present invention proposed a means with a hollow shaft tube or what is called just a shaft tube which the inner material was removed from, for the purpose of cutting the weight and the cost by saving the material, in Japanese Patent Application No. 291775/86.
When a functional member such as a paper feed roller is tried to be fixedly secured on the shaft tube, conventionally one of the following means or the like was obliged to be adopted, that is, a) to secure by using adhesive or by setting a screw or pin into an hole opened at a part of the functional member, b) to secure by pressing the functional member onto the knurled shaft tube, or c) to secure by injecting a material to mold the functional member incorporated with the shaft.
However, those means brought about a problem such as a) to be easy for the adhesion to weaken as time elapses, b) to be likely for the shaft tube to collapse due to high pressure for forming knurl on the shaft tube, or c) a fear for the shaft tube also to collapse due to high pressure and a complicated process to be needed in injection molding.
The approaches using the conventional arts with a shaft tube as above introduce a problem such as defects in workability or function, and anyway could not be satisfactory securing means.